On Thu, Aug 07, 2025 at 07:13:50PM +0600, Svetlana Parfenova wrote: > On 07/08/2025 00.57, Kees Cook wrote: > > On Wed, Aug 06, 2025 at 10:18:14PM +0600, Svetlana Parfenova wrote: > > > Preserve the original ELF e_flags from the executable in the core dump > > > header instead of relying on compile-time defaults (ELF_CORE_EFLAGS or > > > value from the regset view). This ensures that ABI-specific flags in > > > the dump file match the actual binary being executed. > > > > > > Save the e_flags field during ELF binary loading (in load_elf_binary()) > > > into the mm_struct, and later retrieve it during core dump generation > > > (in fill_note_info()). Use this saved value to populate the e_flags in > > > the core dump ELF header. > > > > > > Add a new Kconfig option, CONFIG_CORE_DUMP_USE_PROCESS_EFLAGS, to guard > > > this behavior. Although motivated by a RISC-V use case, the mechanism is > > > generic and can be applied to all architectures. > > > > In the general case, is e_flags mismatched? i.e. why hide this behind a > > Kconfig? Put another way, if I enabled this Kconfig and dumped core from > > some regular x86_64 process, will e_flags be different? > > > > The Kconfig option is currently restricted to the RISC-V architecture > because it's not clear to me whether other architectures need actual e_flags > value from ELF header. If this option is disabled, the core dump will always > use a compile time value for e_flags, regardless of which method is > selected: ELF_CORE_EFLAGS or CORE_DUMP_USE_REGSET. And this constant does > not necessarily reflect the actual e_flags of the running process (at least > on RISC-V), which can vary depending on how the binary was compiled. Thus, I > made a third method to obtain e_flags that reflects the real value. And it > is gated behind a Kconfig option, as not all users may need it. Can you check if the ELF e_flags and the hard-coded e_flags actually differ on other architectures? I'd rather avoid using the Kconfig so we can have a common execution path for all architectures. -- Kees Cook
